CardBus is the mobile equivalent of PCI. It is the 32 bit replacement for the 8/16 bit PCMCIA. Its advnatages include bus mastering capability, meaning it lessens the CPU/system load when undertaking intensive I/O. It also allows more data to be transferred. The 22Mbit TI-based cards are cardbus-based, as are all 54Mbit 802.11a products.

Because the formfactor is identical, CardBus cards are often refered to as "PCMCIA cards". A standard PCMCIA card will work in a CardBus slot, but a CardBus device won't work in a regular PCMCIA slot unless it is also backward compatible to standard PCMCIA.

The CardBus standard was released in 1996, so even quite old laptops have CardBus controllers. Some Toshiba laptops allow you to switch between PCMCIA and CardBus support in the BIOS.